I have an Optoma EP 731 DMD video projector that died. The bulb doesn't
light. How do I test the bulb? An ohmeter across the leads reads
infinity. Is this normal?
Thanks.
Slim

"Slim" wrote in message
oups.com...
I have an Optoma EP 731 DMD video projector that died. The bulb doesn't
light. How do I test the bulb? An ohmeter across the leads reads
infinity. Is this normal?


It is open (burned out).

"Charles Schuler" wrote in message
. ..

"Slim" wrote in message
oups.com...
I have an Optoma EP 731 DMD video projector that died. The bulb doesn't
light. How do I test the bulb? An ohmeter across the leads reads
infinity. Is this normal?


It is open (burned out).

The lamp is high intensity discharge device and should normally read an open
circuit. You can check the lamp only on a known working ballast. Does the
projector have any diagnositcs? Most have an indicator to show when the
lamp fails.

Leonard

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Slim wrote:
I have an Optoma EP 731 DMD video projector that died. The bulb doesn't
light. How do I test the bulb? An ohmeter across the leads reads
infinity. Is this normal?
Thanks.
Slim



Depends on the bulb. If this is a discharge lamp as modern projectors
use then yes, it will read open circuit until you get a few thousand
volts to ionize the gas. If it's a very old projector with a tungsten
lamp then it should read close to zero ohms cold.

"Leonard Caillouet" wrote in message
. ..

"Charles Schuler" wrote in message
. ..

"Slim" wrote in message
oups.com...
I have an Optoma EP 731 DMD video projector that died. The bulb doesn't
light. How do I test the bulb? An ohmeter across the leads reads
infinity. Is this normal?


It is open (burned out).

The lamp is high intensity discharge device and should normally read an
open circuit. You can check the lamp only on a known working ballast.
Does the projector have any diagnositcs? Most have an indicator to show
when the lamp fails.

Are you sure? It seems to be a halogen or metal halide type.

"Charles Schuler" writes:

"Leonard Caillouet" wrote in message
. ..

"Charles Schuler" wrote in message
. ..

"Slim" wrote in message
oups.com...
I have an Optoma EP 731 DMD video projector that died. The bulb doesn't
light. How do I test the bulb? An ohmeter across the leads reads
infinity. Is this normal?


It is open (burned out).

The lamp is high intensity discharge device and should normally read an
open circuit. You can check the lamp only on a known working ballast.
Does the projector have any diagnositcs? Most have an indicator to show
when the lamp fails.

Are you sure? It seems to be a halogen or metal halide type.

Also note that for a halogen or HID lamp, if you touched the glass with
your fingers, it must be cleaned with alcohol or acetone before powering
it. Finger oils absorb UV and etch glass. It will explode in short order.

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Repair | Main Table of Contents: http://www.repairfaq.org/REPAIR/
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| Mirror Sites: http://www.repairfaq.org/REPAIR/F_mirror.html

Important: Anything sent to the email address in the message header above is
ignored unless my full name AND either lasers or electronics is included in the
subject line. Or, you can contact me via the Feedback Form in the FAQs.

Charles Schuler wrote:
"Leonard Caillouet" wrote in message
. ..

"Charles Schuler" wrote in message
m...

"Slim" wrote in message
egroups.com...

I have an Optoma EP 731 DMD video projector that died. The bulb doesn't
light. How do I test the bulb? An ohmeter across the leads reads
infinity. Is this normal?


It is open (burned out).

The lamp is high intensity discharge device and should normally read an
open circuit. You can check the lamp only on a known working ballast.
Does the projector have any diagnositcs? Most have an indicator to show
when the lamp fails.


Are you sure? It seems to be a halogen or metal halide type.




Metal halide = HID = high intensity discharge, this is *not* the same as
tungsten halogen which is just a fancy incandescent lamp. Two completely
different principals of operation. They both are made of quartz and
contain halide salts as part of the gas fill but that's where the
similarities end.

"James Sweet" wrote in message
news:t1Eoh.3217$2D.259@trndny07...
Charles Schuler wrote:
"Leonard Caillouet" wrote in message
. ..

"Charles Schuler" wrote in message
om...

"Slim" wrote in message
legroups.com...

I have an Optoma EP 731 DMD video projector that died. The bulb doesn't
light. How do I test the bulb? An ohmeter across the leads reads
infinity. Is this normal?


It is open (burned out).

The lamp is high intensity discharge device and should normally read an
open circuit. You can check the lamp only on a known working ballast.
Does the projector have any diagnositcs? Most have an indicator to show
when the lamp fails.


Are you sure? It seems to be a halogen or metal halide type.


Metal halide = HID = high intensity discharge, this is *not* the same as
tungsten halogen which is just a fancy incandescent lamp. Two completely
different principals of operation. They both are made of quartz and
contain halide salts as part of the gas fill but that's where the
similarities end.

Thanks for the info. Still learning!